@colindjones - I was likely writing this as your question was being moved, so it is now disconnected from your question.
Colin - so long as you are doing something that allows filtering the list to less than 500 species (thus the birds seen in Ontario that have been observed here but not by you in the province would work, but something like moths, you would need to filter it to a finer family) you can do what is described here :
https://forum.inaturalist.org/t/observation-needs/11293/6
Click the Not in Common to filter down to species youve not reported